Synthetic vision system brings the world into focusSynthetic vision system brings the world into focus

May 1, 2008By Dave Hirschman

A slate gray winter sky allowed for marginal VFR conditions at Garmin’s home airport in Olathe, Kansas—but inside the company’s Cessna T182 test bed, the surrounding topography, obstacles, and air traffic were visible in sharp, colorful, three-dimensional relief. “Synthetic vision,” a GPS-derived view of the world, is the centerpiece on a bright, 12-inch primary flight display (PFD) that showed a mesmerizing series of rectangular “highway-in-the-sky” boxes passing like fence posts on a rural highway.

A slate gray winter sky allowed for marginal VFR conditions at Garmin’s home airport in Olathe, Kansas—but inside the company’s Cessna T182 test bed, the surrounding topography, obstacles, and air traffic were visible in sharp, colorful, three-dimensional relief. “Synthetic vision,” a GPS-derived view of the world, is the centerpiece on a bright, 12-inch primary flight display (PFD) that showed a mesmerizing series of rectangular “highway-in-the-sky” boxes passing like fence posts on a rural highway. In the center of the picture, a circular green “flight path indicator,” or velocity vector, predicted the airplane’s trajectory. All around, the hills, lakes, and obstacles of eastern Kansas appeared on the PFD as they would on a clear VFR day.

“Just put the flight path indicator in the middle of the boxes,” said Tom Schaffstall, a Garmin test pilot, as he programmed the airplane’s G1000 for an LPV approach to Runway 36 at the New Century Aircenter. “It’ll take us right to the runway aiming point every time.”

Garmin has been working secretively and intensively for two years to add synthetic vision system (SVS) to its G1000 avionics suite, and by early April 2008, the company expected its efforts to receive final FAA certification. The two-panel, G1000 system has become a standard feature on many new general aviation airplanes and has made analog gauges all but extinct in new airplanes ranging from Cessna 172s to Embraer Phenoms.

Diamond’s DA-40 will be the first aircraft with an SVS supplemental type certificate (STC), and other manufacturers of aircraft with G1000 cockpits are expected to follow. More than 5,000 airplanes are equipped with G1000s, and each unit is capable of being updated with SVS.

Garmin won’t sell the SVS software directly to consumers. The company provides it only to aircraft manufacturers and allows them to get STCs and set SVS prices and deliveries. Garmin says the installation process takes minutes and requires no additional hardware.

Once SVS software is installed, pilots are provided with an incredibly detailed, three-dimensional, GPS-derived view of their surroundings, regardless of the weather conditions. Mountains appear as they would through the windshield, and the flight path indicator and a horizontal “zero pitch line” give clear indications if the airplane will clear them.

The G1000’s internal TAWS (terrain awareness and warning system) shades the approaching terrain yellow, then red, as the threat of a collision increases and gives audible “pull up” commands. Obstacles such as radio towers, bridges, and power lines appear with identical warnings. Garmin updates its obstacle database every 30 days and terrain annually.

Garmin’s test aircraft is equipped with traffic information service (TIS), a traffic warning system that gathers information from FAA radar and displays it on the PFD. Other aircraft in flight appear as white diamonds that grow as they get closer. While following another aircraft on final approach to New Century Aircenter, the airplane’s position seemed to jump erratically from one side of the extended centerline to the other. Schaffstall said the jerky motion of the traffic was a function of relatively slow radar updates—not turbulence.

“We’re getting a feed from Kansas City,” he said. “It only updates the position once every six seconds or so, while the GPS updates continuously.”

Between two ridgelines

Inside the 182, Schaffstall programmed the G1000 to fly a full ILS approach, and the airplane never waivered. But would SVS be useful for hand-flying an approach? Would the process be more intuitive than aligning the localizer and glideslope needles?

Schaffstall clicked off the autopilot and handed over the controls. We were headed back to New Century Aircenter for an LPV approach to Runway 36. It was to be my first LPV approach ever, as well as my first behind a G1000—and we had a 27-knot crosswind at our altitude of about 3,000 feet. But simply flying through the magenta pathway boxes kept us on course during the brief, cross-country portion of our flight, and our altitude barely wavered. The boxes made a curving, descending path onto our final approach course, and lining them up was intuitive and relatively simple, despite the wind. The boxes can be set to guide the aircraft between two airports, two waypoints, or they can show the entire instrument flight plan and approach. They can also be turned off if pilots prefer a less cluttered screen.

At a range of eight miles, the runway came into view on the PFD as a white rectangle that grew steadily during the approach. At two miles, the runway numbers became visible on the graphic representation. The transition from head-down to head-up was much simpler than usual because the graphic view of the world corresponded with such fidelity to the actual situation outside. The only difference was shifting from brilliant color in the head-down mode to the dreary, black-and-white reality of a February day in the Midwest.

The SVS field of view is about 65 degrees laterally and 48 degrees vertically. The G1000 PFDs come in three sizes: 10, 12, and 15 inches. If the airplane’s pitch attitude exceeds the SVS vertical limits, the PFD reverts to the regular blue-over-brown indications of the standard G1000 display. When flying over water, the SVS separates light blue sky from dark blue water with a sharp, white zero-pitch line. At all times, a yellow inverted V provides the attitude representation.

Garmin encourages pilots to use the G1000’s PFD and MFD for tactical and strategic decision-making. The PFD shows terrain, traffic, and instrument approach guidance of immediate interest, and the MFD gives the big-picture maps, charts, and weather displays that allow for long-range planning.

“Once you’ve flown with SVS, a traditional display doesn’t seem adequate anymore,” Schaffstall said. “I flew it around Asheville, North Carolina, and flew down between two ridgelines. The situational awareness was incredible. Not only could you see the ridgelines, but you could see rock formations on the ridgelines—and the picture from the display matched exactly what you could see with your own eyes.”